Process and apparatus for roasting and reducing iron oxide and other oxide ores



Oct. 30, 1945. w CLARK 2,387,882

PROCESS AND APPARATUS FOR ROASTING AND REDUCING IRON OXIDE AND OTHEROXIDE ORES Filed June 29, 1943 fl a? .I. Wx 47/ M l i w Patented Oct.30, 1945 PROCESS AND APPARATUS 'FOR ROASTING AND REDUCING IRON OXIDE ANDOTHER OXIDE ORES Walter Gordon Clark, Los Angeles, Calf., assignor toClarkiron, Inc., a. corporation of Nevada.

Application' June 29, 1943, Serial No. 492,?32

' 6 Claims.

My invention relates to a process and apparatus for roasting andreducing iron and other oxides and oxide ores, and more particularly toone in which the heat generated in the manufacture of the gases used toroast the ore aids in the manufacture of the reducing agent used toreduce the oxides or ores, and at the same time substantially aids inthe necessary heating during the reduction of said oxides or ores bysaid reducing agent.

Hydrocarbon gas, natural or manufactured, is broken to Hz and C. The Cis recovered and Hz is used as the reducing agent. In my invention, alliron ores, including magnetite, can be usedthus permitting recovery ofiron and oth'er metals from magnetic oxide ores.

One of the purposes of my invention consists in burning natural gas witha limited amount of air to form water vapor and carbon monoxide (HzO andCO). This heated gas is then burned to CO2 to roast 'the ore and at thesame time 'the heat of combustion to CO is used to break otherhydrocarbon or natural gas, mostly methane, into carbon and hydrogen (Cand Hz). Th'e carbon is deposited on the surface of the heated chamber,scraped off, and recoverable as a byproduct while the hydrogen (Hz) isused as the reducing gas to reduce the oxide ores.

Other advantages of my invention will be ap parent from the followingspecification and drawing of the preferred embodiment of my invention.

In the drawing:

Figure 1 is a longitudinal section of th'e lower part of my roaster andreducer.

e bustion chamber 3. Air in the proper proportion to burn this naturalgas to carbon monoxide and Water vapor is admitted through a surroundingpipe 4, which is concentric with the pipe l but of larger diameter andattached thereto. Gas and air is admitted through the ports 5 into thecombustion chamber 3. I provide a lighting port 6 from the outside ofthe furnace extending into the combustion chamber 3, through which anylighting mechanism can be inserted to ignite the gases in the combustionchamber 3. The partially burned or reacted gases pass from thecombustion chamber 3 through the stack 'I past the butterfly valve 8into a roasting chamber 9. In this chamber the carbon monoxide (CO). isburned to carbon dioxide (COz) by the admission through a valve o ofair. Further natural or hydrocarbon gas can be admitted through a valveli to aid in preheating the roasting furnace. After the roasting furnacehas been sufliciently heated to roast the ores, the valve H can beclosed and merely the gas entering through the stack 'I and furthersupply of air used to roast the ore.

I provide the roasting chamber 9 with a series of downwardly pointingtruncated cone segments z and a series of upwardly pointing cones !3.The upwardly pointing cones I3 are of greater diameter than the openingsin the downwardly pointing truncated cones and are given a verticalreciprocating motion adjustable as to the magnitude and the frequency ofthe movement. The

magnitude and the frequency of the movement are adjusted to the rate atwhich the ore is roasted and reduced.

The downwardly pointing truncated cones 12 are firmly set in the bricklining |4 of the roaster. The upwardly pointing cones |3 are segmentsassembled loosely on the vertical shaft |5 and each segment looselyattached to the vertical shaft by the collars 16. Each set of cones |3can 'move to a stop on the fixed cones l2 or may stop on granules of oreunder the cone and limit the movement of the cone segments but permitthe vertical shaft |5 to move to a greater extent through the cones I3.The vertical motion is generated by any type of hydraulic pressure orpneumatic pressure in a cylinder or by a reciprocated motion generatedby a crank or an eccentric.

On the upward limit of the movement of the cones l3, the flow of ore tobe heated or roasted is shut off by the top cone I' substantiallycontacting the lower end of a vertical loose cylindrical feed chute |8through which the ore is fed to the roaster. On the downward movement,the cones |3 contact the next lower downwardly pointing cone,interrupting the flow of material. On the next upward movement, thepreviously admitted material is released and fiows by gravity down thefixed cone !2 to the next upwardly pointing cone l3, thus allowing theore to move downwardly a, short distance and stop on each stroke whileadditional ore is entering at the top of the roaster.

The cones l2 are set at an angle greater than the angle of repose of theore permitting the ore or granular material to flow on these cones bygravity. The movable or upwardly pointing cones |3 are set at a lesserangle or slightly less than the angle of repose of the ore undertreatment. Thus, the ore rests on the upwardly pointing cones untilmoved downwardly by the reciprocating motion of the cones l3, and whendischarged from the movable cones to the fixed cones l2 the materialmoves 'down the fixed cone by gravity. All cones I 2 and !3, except thetop and the bottom cones I'I and l9, respectively, are equipped withfiues 20 projecting above the cone a greater distance than the depth ofthe ore on the cone. These flues 20 permit free movement of heat fromthe burners as the products of combustion move upwardly from' the stack1, thereby heating the cones and subjecting the ore thereon to a heatingand roasting treatment. These flues may be set at an angle to direct theheated gases to move on a. circular or spiral path. The bottom cone s,below the point at whichthe combustible gases enter the roaster, ispositioned to allow the roasted ore to move downwa'dly on the sharperangle of this cone by gravity into the reduction chamber 2 I. The cone I9 is positioned to permit gases rising through the ore in the reductionchamber to pass horizontally through the ore to an independent dischargeoutlet 22 for further use; or upon closing the outlet 22 the gasesrising through the ore will mix with the gases from stack 1 and burn inthe roaster.

The heated comb-ustible gases enter the roaster below the bottom .cone19 and the gases move through the fiues in the stationary and movablecones |2 and |3 -upwardly to a. stack 23 or vent, through which they aredischarged to the atmosphere, producing draft as required.

To provide a reducing'gas for the reduction of the roasted ore movingdownwardly through the reduction chamber ZI, I admit natural gas orother hydrocarbon gas through the valve 24 to the chamber 25, which ison the exterior side of the combustion chamber 3 and separated therebyby a metallic wall 26. The heat of combustion of the natural gas and airin the combustion chamber 3 passing through this wall 26 and the heat'of the reduced ore in the annular chamber ZI is sufiicient to break thenatural gas (which is principally methane (CHQ) in the chamber 25 tohydrogen (Hz) and carbon (C). The carbon either falls free down tohopper 21 and into spilet 22 for further use and not pass up through themaster. I provide pyrometers 3| to record the temperatures of thereducing gas in the stack 21.

To reduce friction on the walls of the reduction chamber 2I, I havegiven the walls an angle of approximately 4%, making this chamber ofgreater area at the bottom. To provide for vertical expansion, a trap 32is provided at the upper end of the stack which fits over the outer wall33, allowing the stack wall to move therein. A gas-tight expansion jointor bellows 35 of any type can be placed to connect the main body 36 ofthe rcaster to the outer wall 33 of the reduction chamber. To providesupport for stack 'l in the center of the reduction chamber 2l,projecting supports 34 are attached to stack 'I and rest on an ofi'setin the outer wall of stack 2l. Stack 1, combustion chamber 3, and thecover of gasbreaking chamber 25 are Suspended from supports 34. Theouter wall of chamber 25, the outer wall 33 of stack 2l, and the weightof ore and metal in ZI are supported on feet 31 resting on plate S,which expand upwardly.

While I have described the prefe'red embodiments of my invention, I amnot limited to any of the details set forth therein except asspecifically described in the appended claims.

I claim:

1. In the combination of an ore roasting and reducing furnace, means tosupply ore to said roasting and reducing furnace, a combustion chamberwherein hydrocarbon gas and air are burned to form a roasting gas, achamber surrounding said combustion chamber wherein natural gas isbroken into hydrogen and carbon to form a reducing gas by the heat ofcombustion in said combustion chamber and the heat of the reduced ore, aroaster into which the roasting gas from said combustion chamber isfurther burned with air, a series of fixed downv wardly sloping cones insaid roaster. a series ral discharge 28, where it is drawn off, or thecarbon from the broken gas is deposited on the walls 26 andscrapedtherefrom -by a, revolving scrape' 29, then falling down into thehopper 21 and the spiral discharge 28.

The hot Hz or reducing gas then passes through opening 40 into thereduction chamber 2l where it encounters the ore descending from theroaster. At the same time, the ore and gas are heated up to atemperature substantially around 1850. F. by the induction coils 30, andheated to 1950 F. by combustion of the gas to CO. At this and lowertemperatures the hydrogen reduces the oxide ores to metal and watervapor, and the vapor and excess Ha pass up through the reduction Ichamber 21 and the discharge outlet 22, the reof vertically movableupwardly sloping cones concentric with said downwardly sloping cones.the movement of said upwardly sloping cones permitting ore admitted tothe top of said cones to move downwardly over said cones untildischarged down into a reduction chamber into which the reducing gas isadmitted and where said ore in reduced by said reducing gas, and portsover each cone for passing said roasting gas.

2. In the combination of an ore roasting and reducing furnace, acombustion chamber wherein natural gas and air are burned to form aroasting gas, a chamber surrounding said combustion chamber whereinnatural gas is broken into hydrogen and carbon to form a reducing gas bythe heat of combustion in said combustion chamber, a roaster into whichthe -roasting gas from said combustion chamber is further burned withair, a series of fixed downwardly sloping cones in said roaster, aseries of vertically movable upwardly sloping cones concentric with saiddownwardly sloping cones, the movement of said upwardly sloping conespermitting ore admitted to the top of said cones to move downwardly oversaid cones until discharged down into a reduction chamber into which thereducing gas is admitted and where said ore is reduced by said reducinggas, ports over each cone for passing said roasting gas, and a valve forneutralizing the pressure of the roasting gas and the reducing gas atthe entrance to said roaster.

3. In the combination of an ore roasting and reducing iurnace, means tosupply ore to said roasting and reducing furnace, a combustion chamberwherein .natural gas and air are burned to form a roasting gas, achamber surrounding said combustion chamber wherein natural gas isbroken into hydrogen and carbon to form a reducing gas by the heat ofcombustion in said combustion chamber and heat in the reduced ore withmeans for passing the reducing gas into contact with the ore underreduction, a roaster into which the roasting gas from said combustionchamber is further burned with air, a series of fixed downwardly slopingcones in said roaster, a series of vertically movable upwardly slopingcones concentric with said downwardly sloping cones. the movement ofsaid upwardly sloping cones permitting ore admitted to the top of saidcones to move downwardly over 'said cones until discharged down into areduction chamber into which the reducing gas is admitted and where saidore is reduced by said reducing gas, the outer walls of said reducingchamber sioping outwardly from the vertical to reduce friction in saidreducing chamber, and ports through each cone for passing said roastinggas.

4. In the combination of an ore roasting and reducing fumace, means tosupply ore to said roasting and reducing furnace, a combustion chamberwherein natural gas and air are burned to form a roasting gas, a chambersurrounding said combustion chamber wherein natural gas is broken intohydrogen and carbon to form a reducing gas by the heat of combustion insaid combustion chamber and the heat of the reduced metal, a master intowhich the roasting gas from said combustion chamber is further burnedwith air, a series of fixed downwardly sloping cones in said roaster, aseries of vertically movable upwardly sloping cones concentric with saiddownwardly sloping cones, the movement of said upwardly slopng conespermitting ore admtted to the top of said cones to move downwardly oversaid cones until discharged dom into a reduction chamber into which thereducing gas is admitted and where said ore is reduced by said reducinggas, and ports over each cone for passing said roasting gas, and aheater surrounding said reduction chamber.

5. In the combination of an ore roastng and reducing furnace, acombustion chamber wherein natural gas and air are burned to CO to forma combustible gas for roasting, a chamber surrounding said combustionchamber wherein natural gas is broken into hydrogen and carbon to form areducing gas ,by the heat of combustion in said combustion chamber, aroaster having therein a series of fixed downwardly sloping cones, aseries of verticaly movable upwardly sloping cones concentric with saiddownwardly sloping cones, the movement of said upwardly sloping conespermitting ore admitted to the top of said cone structure to movedownwardly over said cones until discharged down into a reductionchamber into which the reducing gas is admitted and where said ore isreduced by said reducing gas, and ports through each cone for passingsaid roasting gas.

6. In the combination of an ore roasting and reducing furnace, means tosupply ore to said roasting and reducing furnace, a combustion chamberwherein natural gas and air are burned to form a roasting gas, a chambersurrounding said combustion chamber wherein natural gas is broken byheat into hydr'ogerr and carbon to f orm a reducing gas by the heat ofcombustion in said combustion chamber and the heat in the reduced ore, aroaster in which ore moves downwardly and is roasted by said roastinggas, a reduction chamber into which said roasted ore moves down and intowhich the reducing gas is admitted and where said ore is reduced by saidreducing gas.

WALTER GORDON CLARK.

